Nisin dissipates the proton motive force of the obligate anaerobe Clostridium sporogenes PA 3679

Abstract

The influence of nisin on the proton motive force (Δp) generated by glucose-energized cells of the obligate putrefactive anaerobe Clostridium sporogenes PA 3679 was determined. The components of Δp, the transmembrane potential (Δψ) and the pH gradient (ΔpH), were determined from the distributions of the lipophilic cation [3H]TPP+ ([3H]tetraphenylphosphonium bromide) and [14C]salicylic acid, respectively. The cells maintained a constant Δp of -111 mV, consisting of a ΔpH of 0.4 to 1.0 pH units at an external pH of 5 to 7 and a Δψ of -60 to -88 mV. Nisin, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and N,N'- dicyclohexylcarbodiimide (DCCD) at pH 6.0 elicited the complete release of preaccumulated [3H]tetraphenylphosphonium bromide and [14C]salicylic acid, with a concomitant depletion of Δψ and ΔpH. Nisin and DCCD caused rapid drops in intracellular ATP levels from 1.2 to 0.01 and 0.06 nmol/mg of cells (dry weight), respectively. Cells exposed to nisin and DCCD lost the ability to form colonies, thus suggesting that Δψ and ΔpH are necessary for cell viability. The data suggest that depletion of Δp and exhaustion of cellular ATP reserves are the basis for nisin inhibition of C. sporogenes PA 3679.